Cylon is an acronym for Cybernetic Life-form Node. It was designed by Graystone Industries as a combat robot. The first prototypes lacked adequate artificial intelligence for combat, but with the installation of the meta-cognitive processor in a U-87, along with data from Zoe Graystone's avatar, one prototype excelled at this function.
After successful elimination of terrorist threat during „Apotheosis“, Cylons became massively used specially in low qualified professions. Although Cylons were still considered as things (from Cylon perspective – slaves). Most of Cylons were converted to monotheism (in the extreme form of STO). These circumstances led to the First Cylon War and to the Fall of Twelve Colonies.